Need rec for IEM's at ~$100... mainly for listening to video game remixes; sound quality and isolation are top priorities... read within

The title says it all... I am in the market for whatever would be the best IEM for my needs. I listen mostly to video game remixes a la OC remix (ocremix.org) which are a bit heavier on the lower end of the register - almost never with vocals on the tracks. Often they have an electronica/trance/hybrid feel to them, but there also are some tracks that are more groove/chill/almost ambient tracks. To get an idea of what we are working with, here for some of my favorites, just to give you an idea of what my type of music is (or at ocr.rainwave.cc you can plug into their audio stream):

I also very occasionally would listen to other stuff (widely ranging from legitimate techno to classical to Billy Joel and everything in between) and might use these IEM's while playing a game on the computer, but these occasions would be infrequent and should not dictate the choice of IEM here.

I hope that you can spare a few minutes and at least listen to 20-30 secs in the middle of each of the tracks I linked above, if not listen through the entire things (because in my opinion this music is that awesome to work to!). This will help you understand what I'm listening to.

If there is an IEM at anywhere around or less than $100 (could go a bit higher if it would be justified) that would work here, I am interested in grabbing it. Most important to me, aside from overall sound quality, is isolation. Not only do I not want to hear what's going on around me, but I don't want the people around me to hear what I am listening to, even if it is loud. I wear these a few hours at a time every day.

Through my research, it looks like the HiFiMan RE-400 or the Etymotic Research HF5 may be my best options, but since I haven't been in the market for a new set in many years, I wanted to get you guys' take on it. Any thoughts?

I guess I should clarify a couple of things... but first, thanks for those recs... they all look good to me (especially for my type of music), with the RHA MA750 possibly edging the Yamaha EPH100's out for the top spot. To clarify my listening conditions... typically, these would be used in an office setting where there may be people kicking around a bit, but it is fairly quiet (aside from the damned ventilation holes which I can always hear with my current cheap buds I am using since my last good pair broke). I don't really need anything super durable. Also, I generally listen through programs that have equalizers so I do have that going for me. On occasion I may listen through my phone but this would be rare.

Would this help you lean toward one or the other of those recommended in-ears you listed?